Today's wireless communication systems provide a multitude of functions in addition to traditional mobile telephone communications, such as providing internet access and email service for mobile devices operating in such portable communication systems. Third generation (3G) portable communication protocols, such as wideband CDMA (WCDMA) or CDMA2000, support internet protocol (IP) multimedia subsystem (IMS) communications. While a mobile device using IMS is limited to a single local IP address and server port that is associated with a specific Private User Identity (Private ID), the single secure IMS connection can be used to support a multitude of services implemented by numerous User Agents (UA) all executing on the same mobile device, where a UA is an application which uses the IMS connection in association with a Session Initiation Protocol (SIP). Unfortunately, when an IMS request is received outside of a session or dialogue, it may not be immediately clear to which UA the request is targeted. Consequently, a complicated algorithm based on message contents (e.g., method, feature tags, body, etc.) may be required to resolve the UA destination of the IMS request within the mobile device.
For mobile devices which support globally routable user agent uniform resource identifiers (GRUUs), a different GRUU can be registered for each of the UAs using a specific IMS connection. While mechanisms for matching caller preferences contained in incoming SIP requests to registered callee preferences in order to determine a target contact address currently exist, even if the SIP request is found to match a specific registered GRUU, possibly one of a set of GRUUs all bound to the same contact address, there is currently no means of indicating the selected GRUU to the mobile device. One proposal is to use a new SIP URI parameter that a mobile device may add to a GRUU for the purpose of identifying it. This parameter is opaque to the proxy server handling the domain. However, when the server maps the GRUU to the contact bound to it, the server will copy the grid parameter into the contact. As a result, when the UA receives the request, the Request URI will contain the grid parameter it placed in the corresponding GRUU. This mechanism can only be used to identify the GRUU to which a SIP message was explicitly addressed (i.e., SIP request addressed to a GRUU instead of an Address of Record (AOR)). It cannot be used to identify the GRUU that was selected as a result of the network matching caller preferences to registered callee capabilities (i.e., SIP request addressed to an AOR).
Thus, what is needed is a method and apparatus for IMS to include in a SIP request addressed to an AOR and received outside of a dialog, an indication of the GRUU that was selected as a result of matching caller preferences with callee capabilities so that, upon receiving the request, an IMS terminal can use the indicated GRUU to easily route the SIP request to the targeted UA. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.